It is estimated that about 25% of the world crop production is lost due to microbial spoilage, of which spoilage by fungi is by far the most important cause. Not only from an economical point of view, but also from a humane point of view it is of great importance to prevent spoilage of food products. After all, in many parts of the world people suffer from hunger.
In that respect bananas are an important crop. Bananas are ranked fourth after rice, wheat and maize in human consumption. The banana plant is an herb belonging to the genus Musa and is grown in more than hundred countries worldwide. Most of the bananas are consumed by the local population, but also great volumes are exported to e.g. the USA, Europe and Japan.
Both banana plants and banana fruits are sensitive for moulds after harvesting. Panama disease caused by Fusarium oxysporum is the most widely spread disease of banana plants. Also the moulds Mycosphaerella fijiensis and Mycosphaerella musicola cause diseases of banana leaves, the so-called Black and Yellow Sigatoka disease.
In WO 2005/074687 a new antifungal composition containing e.g. natamycin to prevent growth of these spoilage moulds on the banana plants in the field is described. The invention described in WO 2005/074687 offers a solution to protect banana plants in the field against pathogenic moulds.
FR 2 732 191 discloses a method for treating cercosporiose by applying an antifungal composition comprising a fosetyl-Al and optionally a triazole fungicide to the aerial parts of banana plants.
Besides mould growth on banana plants in the field, spoilage of bananas by moulds after harvesting is an issue of major concern. This so called “crown rot” is caused by mould infection after cutting the banana hand from the main stem. At this stage mould spores easily enter the wound via surface liquid and the latex-like sap from the injury. Later during transport and/or ripening the spores can germinate and the moulds grow further into the banana hand and will spoil the bananas. Crown rot can be caused by a number of fungal species. The most important species are Fusarium pallidoroseum, Colletotrichum musae, Verticillium theobromae, Thielaviopsis paradoxa, Lasiodiplodia theobromae, Deightoniella torulosa and Fusarium roseum. Crown rot leads to considerable losses of bananas grown for local consumption and of exported bananas.
To prevent mould damage, after harvesting at least all export bananas, but also many bananas for local consumption, receive a post-harvest treatment on the wound and close to the wound with an antifungal composition. Examples of fungicides applied in today's practice are thiazoles, thiabendazole, benomyl, imidazoles such as imazalil or mixtures thereof.
EP 0 290 155 discloses an absorbent sheet material for application to plant wounds comprising a flexible laminate of a sheet material, a permeable layer, absorbent material and a fungicide e.g. thiabendazole.
U.S. Pat. No. 4,148,891 discloses antifungal preparations of polyene antibiotics dissolved in a mixture of a lower alkanol and a lower alkanoic acid for preventing or inhibiting mould growth on agricultural products such as bananas.
Griffee and Pinegar (1974) examined several fungicides in the treatment of crown rot. Also pimaricin, now known as natamycin, was included in this study. From many other publications it is known that natamycin is a very effective antifungal compound. The authors indeed stated that natamycin showed a broad spectrum action. However, they also concluded that natamycin was not sufficiently active to give satisfactory control of moulds on bananas.
In spite of extensive treatment with the fungicides presently applied, spoilage problems still occur. It is known that moulds rather easily develop resistance to antifungal compounds, which is also the case for several moulds causing spoilage of bananas. When resistant strains develop, selection will take place and mould problems will increase, leading to the use of even higher amounts of fungicides. Further, many of the fungicides applied on bananas cause environmental pollution and human health problems. Also workers safety is an important issue, as it is known that all farm workers come in close contact with high concentrations of these harmful fungicides.
Pineapple belongs to the genus Ananas. It is the second fruit harvest of importance after bananas, contributing to over 20% of the world production of tropical fruits. A large part of the pineapples is consumed as fresh fruit in producing countries, but a considerable amount of pineapples is also exported. Pineapples have problems with respect to crown rot that are comparable with bananas. Also in the case of pineapples a wound vulnerable for moulds is present after harvesting. Moulds may infect the pineapple in a similar way as described for bananas leading to spoilage and economic losses.
Consequently, it can be concluded that there is a severe need for more effective, more environmental friendly, lower-toxicity and less harmful antimicrobial compounds/compositions, e.g. antifungal compounds/compositions, for the treatment of bananas, pineapples and comparable crops.